The present invention relates to devices and methods for supporting operating room systems and, more typically, to devices and methods for supporting surgical circuits in a convenient and easily accessible format. The invention is particularly well-suited to enable pre-assembling of cardiopulmonary bypass circuits.
Effective circulation and control of the patient""s blood are essential to successful heart surgery. This is of particular importance in procedures where the patient is on cardiopulmonary bypass for a significant period of time during surgery. In most modern bypass procedures, blood is oxygenated, treated, and recirculated through the patient by establishing an extracorporeal cardiopulmonary bypass (CPB) circuit in which the blood is mechanically forced by a blood pump through a variety of processing or blood modifying components. A plurality of blood pumps are typically used throughout the CPB circuit to direct the flow of blood through the various CPB circuit components. Generally, the CPB circuit removes blood from the patient, oxygenates the blood, and then returns the blood to the patient. Critics of heart surgery techniques cite a number of drawbacks for procedures that rely on known extracorporeal bypass platforms or circuits.
One well-known drawback of current CPB circuits is the hemolytic effect the multiple mechanical pumps and other instruments in the circuit may have on the blood. For example, a CPB circuit has as many as six pumps for arterial delivery, cardioplegia delivery, cardiotomy suction, left ventricular or aortic root venting, assisted venous drainage, and hemoconcentration. These pumps are typically occlusive roller-type pumps which sequentially pinch and release tubing to affect the desired flow.
Another drawback with current CPB circuits is the potential for detrimental, blood/air interfaces in the long segments of tubing used for cardiotomy suction and venting. Any time blood and air meet and are transported through tubing together, foaming may occur. This foaming results in destruction of clotting factors contained in whole diluted blood circulated through the CPB circuit. This, in turn, results in the release of substances that initiate a cascade of events leading to further dysfunction of platelets, proteins, and eventually organ function in the form of an inflammatory response.
A further drawback of known CPB circuits and procedures is the extended amount of time required by a cardiac perfusionist to set up the circuit prior to performing the procedure. The components of a bypass circuit are typically individually packaged, free-standing units which need to be connected together prior to each surgical procedure. Specifically, the circuit elements must first be located, assembled, and attached to appropriate sterilized circuit tubing. Then, the entire circuit must be flushed out with an inert gas and then primed with a biocompatible fluid, such as blood or saline. The time expenditure increases the cost associated with such surgeries.
Additionally, perfusionists preferably use long lengths of tubing between components to allow for the exchange of bypass components should one of them fail. Furthermore, long lengths of tubing are required to connect venting cannulas and suction tips located in the operative field to blood pumps which then propel the patient""s blood to the cardiotomy reservoir for processing and return to the patient. The excess tubing creates excess tubing volume that must be accounted for by using additional blood or saline when the system is being primed. However, it is in the patient""s best interest to retain the maximum volume of blood within the body, and excessive dilution of the blood can be harmful. Therefore, the need of the perfusionist for long tubing lengths may not be in the best interest of the patient.
Because of the drawbacks associated with conventional CPB circuits, there is a need for improved methods and apparatuses for performing extracorporeal bypass procedures. In particular, there is a need for an improved CPB circuit that reduces trauma to the blood being processed, reduces the time spent by a perfusionist during setup, provides for reliable access to the vasculature, minimizes the risk of infection to the patient by reducing the number of handmade connections required during assembly and setup, and desirably requires only minor modifications to present procedures.
The present invention also provides improved systems, methods, and kits for creating and establishing a bypass circuit for use in a variety of extracorporeal procedures such as cardiopulmonary bypass and the like. The improved system of the present invention advantageously allows a user to assemble the system prior to the bypass procedure with minimal setup time. In particular, the present invention provides methods and apparatuses that combine the advantages of putting a patient on cardiopulmonary bypass with the advantages of reduced blood damage (e.g., minimal hemodilution, minimal hemolysis, and preservation of clotting factors).
A further aspect of the present invention is a system provided in a package that can be adapted to use traditional bypass circuit components. The system preferably reduces the total amount of blood and foreign surface contact, thus reducing the potential for foaming which may destroy clotting factors in the blood. Although the present invention provides advantages in the context of practically all bypass procedures, the invention finds particular use with minimally invasive surgical techniques to minimize patient trauma due to surgery and post-operative effects related to blood bypass.
The present invention also lends itself well in the role of a backup support system for xe2x80x9cbeating heartxe2x80x9d coronary artery bypass procedures known by the acronyms OP-CAB or MID-CAB. These procedures utilize extracorporeal bypass support only in the event of patient instability. The circuit is made available in the operating room, but may not be used. This requires the perfusionist to set up the pump system and dedicate a bypass system prior to the patient need in the event bypass is required, which increases the cost dramatically. Alternatively, the components are made available, and the perfusionist must rapidly connect them into a working system under great pressure. The latter solution increases the patient risk and stress on the medical personnel. In contrast, the present invention permits the entire circuit to be made available in the operating room to be ready at a moments notice, but still remain in the original packaging so that if it is not needed, it is not expended.
In one aspect, the present invention provides a support device for surgical systems including a chassis adapted to support and display in a predetermined arrangement a plurality of interrelated surgical system components. The chassis may comprise a generally planar body having a plurality of openings therein for supporting and displaying the surgical system components. Preferably, the planar body is flexible and includes a plurality of tabs formed by cuts therein. The tabs are bendable from the plane of the planar body and are adapted to releasably retain the surgical system components.
In another aspect, the present invention provides a pre-assembled surgical system comprising a plurality of interrelated surgical system components and a chassis. The surgical system components are supported and displayed by the chassis in a predetermined arrangement. If the surgical system is a circuit, such as cardiopulmonary bypass circuit, the system further includes a plurality of tubes for interconnecting the system components. At least some of the tubes are initially disconnected in the pre-assembled system. The chassis desirably includes a plurality of openings for receiving the surgical system components, and a plurality of retainers provided on the chassis adjacent the openings for retaining the components in the openings.
In a further aspect, a method of setting up a cardiopulmonary bypass circuit is provided by the present invention. The method includes a pre-assembled cardiopulmonary bypass circuit including a plurality of bypass components supported and displayed on a chassis. A plurality of tubes interconnect the bypass circuit components, at least some of the tubes initially being disconnected in the pre-assembled bypass circuit. The method includes interconnecting the bypass circuit components using the tubing.
In a still further aspect, a method of disposing of a surgical circuit is disclosed by present invention. The method includes depositing a chassis having a plurality of used components mounted thereon in a clean bag, and transporting the bag to an infectious waste disposal container.
According to a further aspect of the present invention, an apparatus for use in an extracorporeal bypass procedure comprises a cassette or chassis adapted to have a plurality of mounting elements on which a plurality of bypass components can be affixed. The chassis may be molded from generally strong, lightweight surgical grade materials such as plastic, polymers, and the like. The chassis, which is generally rectangular in shape, will preferably be oriented vertically during use. It should be understood, however, that the chassis may be of different configurations and/or may be adapted for use in other orientations. The chassis will preferably allow the bypass circuit to be primed with less than 1000 cc of fluid, preferably about 800 cc of fluid.
The chassis of the present invention will preferably include a plurality of mounting elements, such as recesses, to which the bypass components can be affixed. If recesses are used, the bypass components are fitted within the recesses. The recesses generally allow for at least partial insertion of the component into the chassis so that some portion of the component remains outside the chassis. This facilitates visual inspection of the operation of these components and also allows for handling, de-airing, and replacement of components as desired. The mounting elements on the chassis allow bypass components to be vertically stacked or otherwise arranged to promote the shortest connections between components and also provide cascading or gravity-assisted flow of fluid. Additionally, the use of the chassis further reduces space occupied by equipment in an already crowded surgical environment.
Channels molded into the chassis may be provided to facilitate the connection of components. The chassis may also come as a pre-assembled bypass circuit with bypass components such as the venous reservoir and tubing integrally molded or formed within the chassis. Problems related to the sterilization process, such as heat-kinked lines or component shifting during transportation, will be greatly reduced or eliminated through the use of the chassis according to the present invention. The chassis may come pre-sterilized, assembled, and pre-connected to comprise a priming circuit or loop, thus reducing setup time from a traditional 20-40 minutes down to about 10 minutes or less, and more preferably about 5 minutes. This is particularly advantageous when rapid set-up of a CPB circuit may be needed to support xe2x80x9cbeating heartxe2x80x9d procedures.
According to a further aspect of the present invention, an apparatus for use in extracorporeal procedures comprises a blood circuit defining a flow path having at least one inlet from which blood arrives from the patient, and at least one outlet where oxygenated blood is return to the patient. The flow path is coupled to least one vacuum source adapted to remove blood from the patient. The flow path may contain a plurality of actuatable occluders to control positive and negative pressures between specific components coupled together by the flow path.
In one aspect, the flow path comprises a plurality of inlet lines leading from the patient to a cardiotomy reservoir and a venous line leading from the patient to a venous reservoir. The cardiotomy reservoir, in turn, may be coupled to the venous reservoir as desired. In this embodiment, the venous reservoir is fluidly coupled to an arterial pump which is coupled to an oxygenator. The output of the oxygenator is typically forked to have an arterial line and cardioplegia line both leading to the patient. An arterial filter and an air detector device may be located along the arterial line. An additional pump and a cardioplegia heat exchanger may optionally be located within the cardioplegia line. Preferably, a one-way valve (retroguard) is located between the venous reservoir and the arterial pump to prevent undesired back flow. Additionally, flows to the cardiotomy reservoir and the venous reservoir are preferably independently controlled by vacuum sources. By using a vacuum source instead of pumps, the level of hemolysis over the course of a surgery may be reduced.